Project - Which board - which shields?

Hey Guys,
I was first looking for a Raspberry Pi and now found Arduino.

So what board should I buy if i need following components:

GPS Shield
Ammeter for up to 30Ampere

It seems to me that the standard Arduino doesn't have enough In/Outputs for all these components.

Can you recommend any Shields i have mentioned?

The solution in the end should be a M2M solution to log GPS data and the current with a server (connected over a mobile data network)

I love the Teensy board and this shows how easy it is to program GPS and recommends a module to use.